U.S. Cancer Death Rate Continues to Fall [Archive]

gdpawel

12-15-2007, 08:28 PM

The paucity of tangible progress with regard to overall cancer mortality may be explained by the well-known phenomenon of "lead bias" (diagnosing earlier in the course of disease), which may account for why a lot of earlier diagnoses provide misleadingly improved statistics, which are not really related either to treatment or to diagnosis.

Prostate cancer is the best example of this. Breast cancer may be another example. It is clear that women who are diagnosed with advanced lesions do poorly and people who are diagnosed with small lesions do better. Tumor stage is always associated with survival and usually with long term survival and curability.

Many men with prostate cancer will never have symptoms or illness from their disease. Prostate cancer is an unpredictable, stochastic, evolutionary process. It is unknowable if early-stage prostate cancer will progress and cause clinical disease in a given patient. Many men happily coexist with prostate cancer and die of something else, like old age.

I would want to see results of a prospective, randomized trial showing actual survival advantages (as well as a comparison of the cost in terms of treatment associated morbidity) before being subjected to a PSA test and the possibility of then getting directed to biopsies and then getting directed to a radical prostatectomy without any clear indication that this is an advantage.

I am a believer in the efficacy of some types of screening procedures, like colonoscopies. Many adenomatous polyps have been found and removed during this procedure. By not having those polyps removed, it is very likely that one would have developed colon cancer along the way.

There have been truly minuscule improvements as a result of adjuvant chemotherapy and the net benefit to the community of breast cancer patients in the real world isn't all that clear. The criticism remains: All of the clinical trials resources have gone toward driving a square peg (one-size-fits-all chemotherapy) into a round hole (notoriously heterogeneous disease).

In academic centers, the patients are entered into clinical trials of square peg in round hole therapy. In the private sector, patients are treated with drugs which generate the most revenue for the treating oncologists, overtreat with infusion chemotherapy, and encourage the patient to receive 2nd, 3rd, and 4th line chemotherapy, regardless of the likelihood of meaningful benefit.

Improvements in overall survival for all patients are owing largely to a marked trend for earlier dignosis and surgical technique. Even this doesn't mean all that many more patients are being cured. If you diagnose someone earlier in the course of disease, of course they'll live long from the time of diagnosis.